A key marketing principle is simply to 'keep in touch'. One way of doing this is via email marketing. If you use this approach, I am sure that you don't blast messages out to strangers (because that's spam, isn't it?).
You may well have noticed that some of your emails 'bounce' / are rejected. Why is this? Well, some of the addresses may be defunct. And some of them are probably being blocked by anti-spam filters. In the trade, this is known as a 'false positives'.
Here is a link to one of the freely available email message checkers. If you run your draft email message through it - you will discover whether it would be considered as spam by the likes of SpamAssassin™. You will receive an instant score + a detailed email report + recommended changes:
I have been using email marketing as part of my marketing communications mix since 2000. I can tell you that even if people register themselves to receive, say, your newsletter, this doesn't mean that their ISP (Internet Service Provider) won't block your stuff. Thereagain, direct mail can get chucked in the bin by a 'gatekeeper' or eaten by the dog, can't it? =)
If you have an internet marketing question for me: just ask!
All the best
Tel: +44 (0)1628 773128
Founder of The Marketing Compass, the marketing mastermind
group for small business owners. www.themarketingcompass.com